On Broadway, the show was a campy hit with crowds who yearned to escape into a decade of mall hair, Swatches, Molly Ringwald and “Saved by the Bell” — not to mention wall-to-wall power ballads from guys in tiger-striped Spandex.

It’s different on the screen, though (and not just because most movie theaters don’t have continuous bar service). Because the actual locations and detailed sets somehow make this all more real. And that makes the stories and characters … more fake.

The basic plot has our heroine, Sherrie Christian — named that, I’m afraid, just so the score can find a place for Night Ranger’s “Sister Christian” — arriving in L.A. to pursue a career as a singer. Soon she meets fellow hopeful Drew Boley, who gets her a job helping him at a fabled rock ’n’ roll bar on the Strip.

But there will be romantic difficulties ahead — including hasty conclusions, career mistakes and the prowling rock star Stacee Jaxx.

The film’s problems begin with who it cast as its leads. Julianne Hough has fresh-scrubbed looks and a lovely voice, and although she’s a little bland, it works for her cornfed character — but why doesn’t the (re-worked) movie script find a way to let this trained dancer actually dance?

Her co-star, Diego Boneta, is even more forgettable. A former kid star from Mexico, he’s still teen-crush material, right down to star-shaped eyelashes. But he doesn’t have the edge of “a city boy, born and raised in South Detroit” or any obvious passion for music — or for Hough.

Which is a problem in a “boy meets girl” plot like this — because if you don’t care whether “boy gets girl” in the third act, the story really has no hold on you in the second.

Luckily there are a lot of other sideshows going on, and a lot of supporting performers grabbing their turns in the spotlight when they can. As every one of them is livelier than Sherrie and Drew, they help hold our attention for awhile, and push things along.

Best of all is Tom Cruise as Stacee Jaxx, the preening rock star who figures as a possible rival. A dissolute musician is always a great character for actors, but here’s an antihero who, finally, isn’t a Keith Richards clone; instead, Jaxx is basically Axl Rose with a few more thorns, an unpredictable and slightly mad star in bottomless chaps.

Cruise is very good in the part, and this shouldn’t be a surprise. He could dance as far back as “Risky Business” (and still busted a move in “Tropic Thunder”) and has become a little too adept at playing charismatic, duplicitous and basically unknowable men. Jaxx is all that plus a bottle of sour mash.

And there are some other fun turns, too, especially by musical pro Catherine Zeta-Jones as an anti-rock censor (who gets to kick up her heels in “Hit Me With Your Best Shot”) and Russell Brand, who needs no special attention to look like a decadent ’80s rock fan. (Less successful are Alec Baldwin and Paul Giamatti — and, yes, they sing, too.)

But with two vanilla leads and a deliberately corny and predictable kids-vs.-squares conflict for the story, there’s not much left to hang on to except the music — and how you feel about that music, all ’80s FM staples from bands such as Twisted Sister, Scorpions and Whitesnake, is critical. If you liked them then … well, you’ll like them now.

But if you hated them then — and personally, I was still playing my old punk records and waiting desperately for grunge to arrive — you’re not going to be any fonder of these tunes blasted through IMAX speakers. (Although I don’t even think Jon Bon Jovi would mind Cruise’s strong cover of “Wanted Dead or Alive.”)

Which is the final question you have to ask yourself: Do you totally love the ’80s? (And by the ’80s I don’t mean the years of Run-DMC, “Straight Outta Compton,” Bad Religion and Sonic Youth.)

If sleeveless Ts and wine coolers are your idea of a retro party, then get in your DeLorean time machine and go — “Rock of Ages” awaits your devil’s horn salutes and Bic lighter tributes.

But if you’re too young, too old, too punk or too urban to get very excited about a new cover version of a Quarterflash song, skip it. You’ve always got your memories to fall back on — and maybe even some totally awesome mixtapes of your own.

Ratings note: The film contains sexual situations and substance abuse.

'Rock of Ages'

(PG-13) Warner Bros. (123 min.)

Directed by Adam Shankman. With Julianne Hough, Diego Boneta, Tom Cruise, Alec Baldwin. Now playing in New Jersey.